"Beyond-thermal-equilibrium" conversion of methane to acetylene and hydrogen under pulsed corona discharge
"Beyond-thermal-equilibrium" conversion of methane to acetylene and hydrogen under pulsed corona discharge
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DOI：
10.1360/02yb9055
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发表时间：
2002-04
影响因子：
9.6
通讯作者：
Aimin Zhu;Xiuling Zhang;Xiao‐Song Li;Weimin Gong
中科院分区：
文献类型：
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作者：
Aimin Zhu;Xiuling Zhang;Xiao‐Song Li;Weimin Gong
在常温常压下，脉冲电晕放电（PCD）下纯甲烷转化的主要产物是c2h2和h22。当能量密度为194 ~ 1788 kJ/mol时，每道次的c2h产率为7% ~ 30%，H产率为6% ~ 35%。这些结果分别高于100 kPa和1100 K时c2h2的最大热力学产率（5.1%）和h2的最大热力学产率（3.8%）。因此，脉冲电晕放电是在环境温度和压力下将甲烷“超热平衡”转化为c2h和H 2的非常有效的工具。在PCD能量密度339 ~ 822 kJ/mol范围内，甲烷转化产物的碳分布为：c2h2 86% ~ 89%， c2h6 4% ~ 6%, c2h4 4% ~ 6%, c3 ~2%, c4 ~1%。通过对相同放电条件下纯甲烷、乙烷和乙烯转化产物的比较，可以得出结论：PCD等离子体中ch4分子与带电电子碰撞产生的chx自由基形成c2h2可能有三种途径：(1)自由基反应直接生成c2h2； (2) c2h2主要由自由基反应生成，通过c2h4脱氢生成c2h2； (3) c2h6是初级产物，然后脱氢生成c2h4（次级产物），再由c2h4脱氢生成c2h2。
At ambient temperature and pressure, C 2 H 2 and H 2 are the dominating products from pure methane conversion under pulsed corona discharge (PCD). When the energy density of 194—1788 kJ/mol was applied, 7%—30% of C 2 H 2 yield and 6%—35% of H 2 yield per pass have been obtained. These results are higher than the maximum thermodynamic yield of C 2 H 2 (5.1%) and H 2 (3.8%) at 100 kPa and 1100 K, respectively. Thereby, pulsed corona discharge is a very effective tool for “beyond-thermal-equilibrium” conversion of methane to C 2 H 2 and H 2 at ambient temperature and pressure. In the PCD energy density range of 339—822 kJ/mol, the carbon distribution of the methane conversion products is found to be: C 2 H 2 86%—89%, C 2 H 6 4%—6%, C 2 H 4 4%—6%, C 3 ~2%, C 4 ~1%. Through comparison of the product from pure methane, ethane and ethylene conversion at the same discharge conditions, it can be concluded that three pathways may be responsible for the C 2 H 2 formation via CH x radicals produced from the collisions of CH 4 molecules with energized electrons in the PCD plasma: (i) C 2 H 2 is formed directly from free radical reactions, (ii) C 2 H 2 is formed through the dehydrogenation of C 2 H 4 , which is formed via free radical reactions primarily, and (iii) C 2 H 6 is the primary product and then dehydrogenates to C 2 H 4 (secondary product) and followed by C 2 H 4 dehydrogenation to C 2 H 2 .